Fix spec using labelExpr and tickBand results in error (#73)

* Fix build instruction

* Write out failed image when baseline doesn't exist

* Add failing test that crashes with:

Failed to deserialize text info: missing field `text`

* Allow test to be missing in text width calculation

treat as empty string and return zero in this case.

DEVELOP.md

@@ -37,7 +37,7 @@ This will produce `target/release/vl-convert`, which should be uploaded to the G
 ### Build Python wheels
 Build the Python wheels with:
 ```
-maturin -m vl-convert-python/Cargo.toml --release -i python3.11 -i python3.10 -i python3.9 -i python3.8 -i python3.7 --strip 
+maturin build -m vl-convert-python/Cargo.toml --release -i python3.11 -i python3.10 -i python3.9 -i python3.8 -i python3.7 --strip 
 ```
 
 This will produce a collection of wheel files in `target/wheels`, which should be uploaded to the GitHub Release below. These wheels must also be uploaded to PyPI with:

vl-convert-python/tests/test_specs.py

@@ -99,6 +99,7 @@ def test_svg(name, as_dict):
         ("stacked_bar_h", 2.0),
         ("remote_images", 1.0),
         ("maptile_background", 1.0),
+        ("no_text_in_font_metrics", 1.0),
     ],
 )
 @pytest.mark.parametrize("as_dict", [False])

vl-convert-rs/src/text.rs

@@ -105,7 +105,7 @@ struct TextInfo {
     weight: Option<String>,
     family: Option<String>,
     size: f64,
-    text: Value,
+    text: Option<Value>,
 }
 
 impl TextInfo {
@@ -136,8 +136,9 @@ impl TextInfo {
         let mut escaped_text = String::new();
 
         let text = match &self.text {
-            Value::String(s) => s.to_string(),
-            text => text.to_string(),
+            Some(Value::String(s)) => s.to_string(),
+            Some(text) => text.to_string(),
+            None => "".to_string(),
         };
 
         for char in text.chars() {
@@ -181,10 +182,17 @@ pub fn op_text_width(text_info_str: String) -> Result<f64, AnyError> {
         Err(err) => bail!("Failed to deserialize text info: {}", err.to_string()),
     };
 
-    if let Some(text) = text_info.text.as_str() {
-        if text.trim().is_empty() {
+    // Return width zero for empty strings and missing text
+    match &text_info.text {
+        Some(Value::String(text)) => {
+            if text.trim().is_empty() {
+                return Ok(0.0);
+            }
+        }
+        None => {
             return Ok(0.0);
         }
+        _ => {}
     }
 
     let svg = text_info.to_svg();

vl-convert-rs/tests/test_specs.rs

@@ -101,9 +101,9 @@ fn make_expected_svg_path(name: &str, vl_version: VlVersion, theme: Option<&str>
         })
 }
 
-fn load_expected_svg(name: &str, vl_version: VlVersion, theme: Option<&str>) -> String {
+fn load_expected_svg(name: &str, vl_version: VlVersion, theme: Option<&str>) -> Option<String> {
     let spec_path = make_expected_svg_path(name, vl_version, theme);
-    fs::read_to_string(&spec_path).unwrap_or_else(|_| panic!("Failed to read {:?}", spec_path))
+    fs::read_to_string(&spec_path).ok()
 }
 
 fn write_failed_svg(name: &str, vl_version: VlVersion, theme: Option<&str>, img: &str) -> PathBuf {
@@ -129,7 +129,7 @@ fn write_failed_svg(name: &str, vl_version: VlVersion, theme: Option<&str>, img:
 
 fn check_svg(name: &str, vl_version: VlVersion, theme: Option<&str>, img: &str) {
     let expected = load_expected_svg(name, vl_version, theme);
-    if img != expected {
+    if Some(img.to_string()) != expected {
         let path = write_failed_svg(name, vl_version, None, img);
         panic!(
             "Images don't match for {}.svg. Failed image written to {:?}",
@@ -156,9 +156,9 @@ fn load_expected_png_dssim(
     name: &str,
     vl_version: VlVersion,
     theme: Option<&str>,
-) -> DssimImage<f32> {
+) -> Option<DssimImage<f32>> {
     let spec_path = make_expected_png_path(name, vl_version, theme);
-    dssim::load_image(&Dssim::new(), spec_path).unwrap()
+    dssim::load_image(&Dssim::new(), spec_path).ok()
 }
 
 fn to_dssim(img: &[u8]) -> DssimImage<f32> {
@@ -190,16 +190,24 @@ fn write_failed_png(name: &str, vl_version: VlVersion, theme: Option<&str>, img:
 
 fn check_png(name: &str, vl_version: VlVersion, theme: Option<&str>, img: &[u8]) {
     let expected_dssim = load_expected_png_dssim(name, vl_version, theme);
-    let img_dssim = to_dssim(img);
-
-    let attr = Dssim::new();
-    let (diff, _) = attr.compare(&expected_dssim, img_dssim);
-
-    if diff > 0.0001 {
-        println!("DSSIM diff {diff}");
+    if let Some(expected_dssim) = expected_dssim {
+        let img_dssim = to_dssim(img);
+
+        let attr = Dssim::new();
+        let (diff, _) = attr.compare(&expected_dssim, img_dssim);
+
+        if diff > 0.0001 {
+            println!("DSSIM diff {diff}");
+            let path = write_failed_png(name, vl_version, None, img);
+            panic!(
+                "Images don't match for {}.png. Failed image written to {:?}",
+                name, path
+            )
+        }
+    } else {
         let path = write_failed_png(name, vl_version, None, img);
         panic!(
-            "Images don't match for {}.png. Failed image written to {:?}",
+            "Baseline image does not exist for {}.png. Failed image written to {:?}",
             name, path
         )
     }
@@ -267,6 +275,7 @@ mod test_svg {
             "line_with_log_scale",
             "numeric_font_weight",
             "float_font_size",
+            "no_text_in_font_metrics"
         )]
         name: &str,
     ) {
@@ -311,6 +320,7 @@ mod test_png_no_theme {
         case("remote_images", 1.0),
         case("maptile_background", 1.0),
         case("float_font_size", 1.0),
+        case("no_text_in_font_metrics", 1.0),
     )]
     fn test(
         name: &str,

vl-convert-rs/tests/vl-specs/no_text_in_font_metrics.vl.json

@@ -0,0 +1,30 @@
+{
+  "$schema": "https://vega.github.io/schema/vega-lite/v5.9.3.json",
+  "description": "https://github.com/vega/vl-convert/issues/72",
+  "data": {
+    "values": [
+      {
+        "column_name": "Prior",
+        "previous_sum": 1.2,
+        "log2_bayes_factor": 2.4,
+        "value": "inal score"
+      }
+    ]
+  },
+  "layer": [
+    {
+      "mark": {"type": "bar", "width": 60},
+      "encoding": {
+        "x": {
+          "type": "nominal",
+          "axis": {
+            "labelExpr": "datum.value == 'Prior' || datum.value == 'Final score' ? '' : datum.value",
+            "tickBand": "extent"
+          },
+          "field": "column_name"
+        },
+        "y": {"type": "quantitative", "field": "previous_sum"}
+      }
+    }
+  ]
+}